For wells in low-pressure formations that do not require the use of steel tubing, corrosion issues that may arise can be avoided by instead employing plastic tubing. In running in tubing using applied pressure, the bottomhole pressure (typically about 800 psi in such low-pressure wells) must still be overcome in order to set packers, and conventional tools can generate just enough force with the application of the equivalent of the bottomhole pressure to set the packers. As packers are typically set inside casings, the force of setting such a tool may be transferred through the tool into the casing. However, the pressure required to generate the setting force is transferred to the well formation through perforations in the casing wall whenever the pump-out plug below the packer is shifted and opens communication between the tubing string and well below the packer, which can result in damage. Also, the pressure can act to cause failures in the connections of the tubing string. Although such failures may in some cases be avoided by strengthening the connections, this may further complicate the normal handling of the plastic tubing. So, since even as little as 800 psi can damage well formations and plastic tubing, there is a need for an improved packer tool that requires the application of less pressure and thus is less likely to cause damage.